Our long-range goal is to understand the cellular and molecular mechanisms of endothelial dysfunction in order to elucidate new targets for pharmacological intervention that will prevent and/or minimize vascular complications of disease. Targeting genes or drugs to specific vessels damaged by disease offers therapeutic promise for reversing that damage and preventing these vascular complications. We will synthesize nanoparticles to deliver tetrahydrobiopterin (BH4), a critical cofactor for endothelial nitric oxide (NO) synthase, to reverse or retard endothelial cell dysfunction in diabetes. A BH4 deficiency in diabetes prevents synthesis of NO and stimulates oxidative injury in blood vessels, leading to endothelial dysfunction. BH4 deficiency may be a common basis for vascular dysfunction in many other diseases (e.g., hypercholesterolemia, hypertension, cardiovascular disease associated with chronic cigarette smoking). The objective of this R21 is to develop biodegradable nanoparticles to specifically target endothelial cells exhibiting impaired function and increase availability of BH4 for NO synthesis. Two specific aims are proposed: (1) Demonstrate modulation of BH4 and NO bioavailability in cultured rat endothelial cells, isolated vessel segments, and blood vessels in vivo by biodegradable nanoparticle-mediated BH4 delivery, and (2) Validate the concept of targeted BH4 delivery to specific endothelial cells by utilizing Lox-1 antibody-conjugated nanoparticles to treat specific cell/vessel targets. Animal models of both type I and type II diabetes will be utilized. This is a novel use of nanoparticles, as most current approaches to nanoparticle-mediated disease treatment involve delivery of agents and/or genes that will bring about death of tumors cells or blood vessels feeding those tumors. Our innovative approach involves bringing a beneficial agent to dysfunctional endothelial cells in order to reverse the effects of disease on those cells and restore vascular function. The proposed nanoparticles will also improve upon viral- based gene therapy because nanoparticles can release encapsulated agents (both genes AND drugs) over a period of days or weeks. Importantly, upregulation of BH4 levels in oxidatively damaged endothelial cells will not only reverse the dysfunction caused by disease but will protect cells from future damage/dysfunction by increasing their endogenous pool of antioxidants. We expect that these biodegradable nanoparticles will provide a versatile preventative and therapeutic intervention for the alarming number of individuals in the United States and worldwide who have vascular impairment associated with a myriad of diseases. PUBLIC HEALTH RELEVANCE: People with diabetes have many health problems in addition to their inability to regulate blood sugar. One of the most serious problems is vascular disease. We will develop microscopic particles (i.e. nanoparticles) that will specifically target vascular cells exhibiting impaired function and bring agents that will repair function and provide future protection from disease-induced damage. Results of our studies will provide insight into potential interventions that can improve life for people with diabetes and minimize the cardiovascular complications associated with this disease.